Learn: How Supplement Quality Verification Works
Most of what decides whether a supplement is worth buying happens before you compare prices: whether an independent organisation has checked what is actually in the bottle, and what that check does and does not cover. These reference guides explain the verification vocabulary we use across every ranking on this site.
Reference guides
- What "Third-Party Tested" Actually Means — The difference between an independent certification and marketing phrases like "lab tested" or "GMP facility" — and what verification does not tell you about whether an ingredient works.
- USP vs NSF vs Informed Sport — What each mark verifies, who each program is aimed at, and how often products in our own dataset carry no third-party certification at all.
Where this gets applied
Certification is one of the layers behind every product ranking on this site — see our methodology for how it is weighed against clinical evidence and cost per effective dose, and our certification gap analysis for how uncommon third-party verification actually is across the products people buy. It's also the last filter, not the first: see how to decide what you actually need before certification even enters the picture, including the specific short list of what most adults should take and skip.